1. Field of the Invention
The present invention relates generally to micro electromechanical structure (MEMS) fabrication, and, more specifically, the present invention relates to the fabrication of a MEMS classifier for charged molecules. In particular, the present invention relates to a classifier for protein molecules that may bear opposite charges and that may have unequal masses.
2. Description of Related Art
One current primary method for separation of charged molecules in solution such as proteins is 2-dimensional polyacrylamide gel electrophoresis (PAGE). This method requires a laborious multi-step preparation of unstable gels, followed by extensive manual working of the gels by skilled technicians. Quantification of the separated molecules is performed typically by visual or photographic inspection of the resulting gels.
A second common method for separation of charged molecules in solution is matrix assisted laser desorption ionization (MALDI) mass spectrometry. This method does not require gels or gel manipulation to separate and quantify a mixture of charged molecules. However, it requires sophisticated vacuum chamber technology, and therefore is too cumbersome for use anywhere but a dedicated lab environment, and requires an expensive hardware investment.
Another technique uses micro fabricated structures. Capillary electrophoresis synchronized cyclic electrophoresis, free-flow electrophoresis, and capillary gel electrophoresis have been demonstrated to separate ions. None of these techniques have the resolving power of 2-dimensional PAGE, and therefore are incapable of separating and quantifying mixtures of many hundreds of different molecules. This general finding corroborates theoretical treatments on the inherent advantage of 2-dimensional chromatography to generate high total peak capacity. High total peak capacity is a measure of the theoretical maximum number of components that can be resolved, or differentiated, by the classifier within a given run.
What is needed is a classifier and method for separating charged molecules that overcomes the problems of the prior art.
The present application also discloses a method of classifying a plurality of substances. In one embodiment, the method comprises providing a solid state classifier comprising a porous medium disposed between at least two electrodes, classifying a plurality of substances by differential mobility chromatography in the porous medium, and classifying the plurality of substances by electrophoresis, wherein the plurality of substances is classified along a plurality of positions within the solid state classifier by fixing charged molecules in place along at least one of the at least two electrodes.